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TDD-TDD Interference Analysis Involving Synchronized WiMAX Systems
3/12/2010
The purpose of this article is to provide guidance on the deployment of adjacent synchronized WiMAX TDD systems in the same geographical area. The target adjacent channel interference rejection figures are assessed based on simulation assuming the same cell characteristics and a consequential frequency separation (guard frequency) is estimated in order to reduce the interference impact between the two systems to a certain acceptable level.
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Matching Differential Port Devices
3/9/2010
Differential signaling is the primary choice for a low power RF interconnection because it provides superior immunity to noise by offering twice the signal swing for a given supply voltage. The out of phase property of a balanced pair has several other benefits: it rejects any common mode interference signal, cancels the even order distortions such IM2, and reduces Electromagnetic Interference (EMI), EMI emission, and susceptibility. However, this presents a challenge for RF designers to integrate differential devices together since the widely used S-parameter matching technique cannot simply be applied. This article depicts a simple generic technique to match differential impedance devices and gives some matching circuit examples.
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Impedance Matching Techniques For Mixers And Detectors
3/5/2010
The use of tables for designing impedance matching filters for real loads is well known. Simple complex loads can often be matched by this technique by incorporating the imaginary portion of the load into the first filter element. This technique is rarely useful for matching diodes because the equivalent circuit for the diode must include several real and imaginary elements. A methodical technique for matching such complex loads to a transmission line will be described. Previous references to similar procedures were empirical in nature. No tables are used, but it is necessary to know the admittance of the diode in the frequency band of interest.
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Practical Antenna Choices For 802.15.4 Enabled Consumer Electronics
3/5/2010
Since being ratified in 2003, the wireless communications standard IEEE 802.15.4 has enjoyed a steadily increasing uptake rate. New and inventive industrial, medical, security and other specialized applications continue to be regularly introduced, employing either open or proprietary protocols riding atop the lower level network layers prescribed by the standard. With mature tools, cost reduced silicon and significant design momentum behind the standard, 802.15.4 enabled products are now set to flood the consumer market space. ZigBee RF4CE is the primary protocol that will power this next wave of deployment.
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Understanding Star Switching: The Star Of The Switching Is Often Overlooked
3/3/2010
Switching is probably the most overlooked and undervalued part of a test system design. Great attention is spent selecting the measurement and stimulus instruments. But more often than not, the signal switching solution does not complement the instruments. It doesn't matter how accurate the instruments
are if the signals pass through a poor switch to get to them. Engineers are familiar with test instruments because they have used them during their school years and at work in the lab and on the bench testing products or debugging new designs. So it's easy for them to select instruments for an automated test
system. On the other hand, the engineers probably did not use switching in day-to-day testing and only consider switching a minor component in an automated test system.
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7 Critical LTE Questions Answered
3/1/2010
No cellular mobile communication technology attracts as much wireless industry attention these days as Long Term Evolution, better known as LTE. Considered by many to be the heir apparent to the mobile broadband throne, LTE holds a great deal of promise. So what's the current state of LTE technology? How big is LTE's upside, really? What hurdles — technical or otherwise — must LTE still overcome to seize the coveted 4G mantle? To determine the answers to these and other key LTE-related questions, RF Globalnet queried four industry experts with vested interest in LTE technology: Jan Whitacre of Agilent Technologies, Mike Barrick of Anritsu Corporation, Mike Press of RFMD, and Andreas Roessler of Rohde & Schwarz. Their responses provide a comprehensive picture of LTE's past, present, and future.
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High-Speed Downlink Packet Access (HSDPA): Challenges For UE Power Amplifier Design
2/23/2010
By Rohde & Schwarz
This Application Note describes the HSDPA and HSUPA uplink channel structure. Challenges for UE power
amplifier design are outlined, and guidelines how to use R&S measurement equipment for testing UE power
amplifiers are provided....
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Is There A Shortage Of Good RF Applications Engineers?
2/9/2010
This article is part of a series of quarterly guest columns by Rick Cory, Applications Engineering Manager, Skyworks Solutions, Inc. In this installment, Cory discusses the recent not-so-subtle shift in RF circuit design, with the field now being divided into two subspecialties: system integrator and RF component designer. He then explores the need for RF applications engineers to fill in the gap between these two camps.
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Bluetooth Low Energy – That Eureka Moment
1/26/2010
One of the nice things about working in technology is those moments when everything clicks and you go "Wow - that's neat". It's something that happens as you work with many of the different standards and you realise that the collective intelligence of those putting it together really is greater than the sum of the parts. Over the years I've had that Eureka moment with a number of wireless standards.
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Fundamentals Of Interference In Wireless Networks
1/13/2010
As wireless systems proliferate worldwide, the number one enemy of wireless systems designers and service providers is signal interference. Interference hampers coverage and capacity, and limits the effectiveness of both new and existing systems. It is an unavoidable fact that wireless communications systems must coexist in extremely complicated signal environments. This article presents the subject of interference and its degrading effects on the performance of wireless networks. It provides a brief theory of operation of communications receivers and antennae, as well as instructions
on how to locate and identify an interfering signal. By Anritsu Company
